Waterproof shaft and method of forming same

ABSTRACT

An excavated mine shaft being provided with inner and outer concrete liners extending the depth of any water-bearing strata through which the shaft extends, and a barrier positioned between said inner and outer concrete liners and being impervious to moisture and expansible upon being subjected to moisture, and the method of forming the same waterproof mine shaft.

United States Patent- Korol et al.

[ 1 Jan. 25, 1972 [54] WATERPROOF SHAFT AND METHOD OF FORMING SAME [72]Inventors: Maurice G. Korol; Thomas H. Holley, both of Omaha, Nebr.

[73] Assignee: Peter Kiewit Sons (30., Omaha, Nebr.

[22] Filed: Sept. 2, 1970 I [21] Appl. No.: 69,034

[52] US. Cl. ..61/4111, 61/36, 61/45 R [51] lnt. Cl ..E21d 5/012 [58]Field ofSearch ..61/41 R.45 R, 63.36, 42. 61/43, 41 A [56] ReferencesCited UNITED STATES PATENTS 835,159 11/1906 Jackson ..61/41 R 1,065,3696/1913 Johnson ..61/41R FOREIGN PATENTS OR APPLICATIONS 908,003 10/1962Great Britain ..61/41 R 44,549 10/1910 Austria ..61/41 R 1,195,7017/1965 Germany... ..61/41 R 41,551 11/1965 Germany ..61/41 R 795,7155/1958 Great Britain ..61/41 R OTHER PUBLICATIONS EngineeringNews-Record, Jan. 4, 1940 (Vol. p. 39) 63 Primary Examiner-Dennis 1...Taylor Atmrney- Peck and Peck 57 ABSTRACT An excavated mine shaft beingprovided with inner and outer concrete liners extending the depth of anywater-bearing strata through which the shaft extends, and a barrierpositioned between said inner and outer concrete liners and beingimpervious to moisture and expansible upon being subjected to moisture,and the method of forming the same waterproof ine shaft.

7 Claims, 4 Drawing Figures WATER HEARING STHATA P'ATENTED JAMES I972 IN VEN TORS Maurice G. Kom/ Thomas H. Ho/ley fix] New ATTORN YSWATERPROOF SHAFT AND METHOD or FORMING SAME This invention relatesbroadly to the-art of water-proofed mine shafts composed of inner andouter concrete liners with a moisture barrier therebetween, and to themethod of forming same; and the nature and objects of the invention willbe readily recognized and understood by those skilled in the arts towhich it relates in the light of the following explanation and detaileddescription of the accompanying drawings illustrating what we at presentbelieve to be preferred embodiments or mechanical expressions of ourinvention from among various other forms, arrangements, combinations andconstructions, of which the invention is capable within the spirit andscope thereof.

In many instances excavated mine shafts penetrate some water-bearingstrata between the earth's surface and the ultimate depth of the mineshaft. The mine shafts in which we are particularly interested areconventionally composed of cylindrical inner and outer concrete liners,and it has been out experience with shafts of this general characterthat where a shaft passes through the aforementioned water-bearingstrata, moisture or water seeps through the shaft lining.

This seepage of water introduces many problems, and it is our primepurpose to prevent this seepage of water through the inner liner. As anexample of the undesirable conditions which are created by this seepageof water, when such seepage occurs, it is necessary to use a costlysystem of pumps, or some other system of water removal, and duringfreezing weather ice often forms on the inside surface of the shaftliner which causes dangerous conditions for both men and equipment, asthe ice is likely to fall causing injury and damage.

The mine shaft of this invention comprises generally inner and outerconcrete liners which normally pass through a water-bearing strata, andwhere the shaft passes through such water-bearing strata we dispose, inposition between these liners, a moistureproof barrier which is formedof any suitable material which is characterized by its capability toexpand when subjected to moisture. It will be recognized that thisexpansive quality of the water-proofing barrier results in a sound sealbetween the inner and outer liners, and this expansive characteristicalso insures a closure of any imperfections which may be present in thebarrier so that the barrier has a self-healing" effect when it issubjected to moisture. These imperfections in the barrier may be causedin any number of ways, for instance, in the installation of the barrierit may be damaged and of course in the manufacture thereof undesirableinterstices may be present in the body of the material of the barrier.One, from among many, materials which may be used with advantage as themoistureproof barrier is bentonite which is a soft, porous materialwhich has the characteristic of expanding upon contact with water up totimes its original volume, which not only produces the aforesaidself-healing" effect but also, due to these expansive qualities,produces an excellent sea]. A further significant advantage of the useof a material for the moistureproof barrier which is endowed with theseexpansive characteristics is that the panels or sheets of the materialneed not be sealed at their edges when they are wound into positionbetween the two cylindrical liners, instead it is only necessary tooverlap the adjacent edges, and it will be appreciated that upon theexpansion thereof, resulting from contact with moisture or water, a goodseal at the edges will be provided.

We have found that it is desirable to make up the sheets or panels ofthe waterproof barrier material in a sandwich manner, so that a paperbacking is provided on at least one face of the material, and preferablyon both. This arrangement substantially facilitates the installation ofthe barrier.

The waterproof mine shaft of this invention is commercially practical,is relatively inexpensive to produce and easy to install.

Our invention also contemplates a novel and ingenious method ofconstructing such water-proofed mine shafts, as will be pointed out indetail hereinafter.

With the foregoing general objects, features and results in view, aswell as certain others which will be apparent from the followingexplanation, the invention consists in certain novel features in design,construction, mounting and combination of elements, as will be morefully and particularly referred to and specified hereinafter.

Referring to the accompanying drawings:

HO. 1 is a vertical, sectional view illustrating a mine shaft which iswater-proofed throughout the length thereof which runs through awater-bearing strata.

FIG. 2 is a top plan view of the water-proofed mine shaft.

FIG. 3 is a perspective view of the waterproof barrier with partsthereof broken away, and with a portion of the paper backing peeled fromthe water-proofed barrier.

FIG. 4 is a view in perspective of the waterproof barrier, with partsthereof broken away, and with a section of the paper backing peeled fromthe barrier disclosing an imperfection in the waterproof barrier.

In the preparation of mine shafts in accordance with the presentinvention the shaft is excavated from the earth's surface 1 to theultimate depth of the shaft. In most instances the excavation extendsthrough a water-bearing strata 3 which extends from the earthssurfacedownwardly along the shaft to some point, such as the point 5, in theexample illustrated in the drawings.

Consideration of FIG. 1 of the drawings clearly indicates that theexcavated shaft 6 is of greater diameter throughout the length thereofwhich passes through the water-bearing strata than is that portionthereof which extends below the water-bearing strata. When the shaft hasbeen excavated into the ground, as described above, a cylindricalconcrete outer liner 7 is positioned within the shaft with its externalcircumferential surface in engagement with the walls of the excavation.The length of the outer liner 7 is substantially equal to the depth ofthe water-bearing strata 3. When this outer liner 7 is positioned, asdescribed, against the wall of the excavation it provides support forthis water-bearing strata and also provides a relatively smooth interiorsurface against which the moistureproof barrier is installed, as will beexplained hereinafter. When the concreting of the outer liner iscompleted a moistureproof barrier indicated generally by the number 11is installed on the inside circumferential surface of the outer liner 7.It will be evident that the moistureproof barrier 11 covers and abutssubstantially the entire inner surface of the outer liner 7. Themoistureproof barrier, indicated in its entirety by the numeral 1 1,consists of a body 13 of the desirable type of water-proofing agent andit is preferable, though not necessary, that the moistureproof barrierbe provided with a paper backing 15 on at least one side thereof, and itmay be provided on both sides thereof if found desirable. It has beenour experience in this art that installation of the water-proofingbarrier is facilitated by providing this sandwich type of article.

The moistureproof barrier is preferably furnished in sheets or panelsand in the installation thereof is wound to conform generally to theinterior configuration of the outer liner 7.

Upon installation of the moistureproof barrier 13 as described above aninner cylinder concrete liner 9 of less diameter than the diameter ofthe outer liner 7 is inserted into the shaft with its exteriorcircumferential surface in engagement with the moistureproof barrier.The inner liner 9 functions as the final surface and as a containmentand protection for the moistureproof barrier 13. It will be noticed thatthe inner liner 9 extends not only through the water-bearing strata 3but also downwardly and therebeyond.

The thickness of the moistureproof barrier depends upon the known orreasonably expected moisture conditions in the water-bearing strata.

It is significant to recognize that we have chosen to use amoistureproof barrier 11 which is characterized by its ability to expandin all directions when it is subjected to the action of moisture. Suchcharacteristics of the moistureproof barrier are highly advantageous fora substantial number of reasons.

When the sheets of the moistureproof barrier have been installed inposition between the outer and inner concrete liners 7 and 9,respectively, where such liners extend through the water-bearing strata,it will be understood that if, and when moisture penetrates the outerliner 7 and comes into contact with the'moistureproof barrier l 1 suchbarrier will expand and will thereby provide a sound seal between thetwo liners preventing moisture from reaching the inner liner 9 andpassing therethrough to cause the difficulties and problems discussedhereinabove.

In using a moistureproof barrier having these expansible characteristicsit is not necessary to seal the adjacent edges of the sheets or panelsof the material, instead the panels at their edges are overlapped asillustrated at in FIG. 2 of the drawings, and due to the expansivequalities of the material, when in contact with moisture or water, agood and sound. seal will be formed between the sheets, or panels, ofthe barrier material. It will be obvious that this elimination of thenecessity for sealing the adjacent edges of the sheets, or panels, savessubstantial time in the installation of the moistureproof barrierwithout sacrificing the resulting excellent seal between the sheets, orpanels of the barrier.

In order for the barrier to properly function as a moistureproofingmeans it will be evident that the body 13 of the barrier must becontinuous and not have interstices or punctures therein through whichmoisture or water could pass. We have found that it often happens thatthe body of the barrier is not continuous and may have openings orimperfections such as 17 therein, as illustrated in FIG. 4. The materialfrom which we make the moistureproof barrier, due to its expansivequalities upon contact with moisture or water, has a self-healing effectwhich operates to close such openings or interstices 17 to provide acontinuous moisture-proofing body. These imperfections in the barrierwhich would reduce or substantially eliminate the water-proofingfunction may be caused by a variety of reasons such as by imperfectinstallation or by some damage that may later be caused.

We have discovered that bentonite is a particularly suitable materialfor use as the moisture-proofing agent. Bentonite is a soft, porous,moisture-absorbing rock composed mostly of clayey material and isendowed with the ability to expand upon contact with water or moistureup to 10 times its original volume which gives this moisture-proofingmaterial an inherent self-healing and sealing effect.

While we have indicated that bentonite functions in a highly 'desirablemanner when it is used as the moisture-proofing agent, we do not wish tolimit this invention to the use of bentonite for other materials havingexpansive characteristics which produce the wanted results may be usedin place of bentonite.

lt is of some significance to appreciate that the inner concrete liner 9should be of such thickness that no concrete inserts, formed holes orreinforcing steel will penetrate through it into the moisture barrier1].

ln the construction of the mine shaft, as disclosed herein, the earth isexcavated whereupon the outer concrete liner 7 which is of a lengthsufficient to extend through the waterbearing strata is placed in theexcavation, whereupon the moisture barrier 11 is positioned in placeagainst the interior circumferential surface of the outer liner and whenthis is completed the inner concrete liner 9 is placed in theexcavation.

We claim:

1. A mine shaft passing through a water-bearing strata in the earth,including an inner liner passing through and extending downwardly intothe earth beyond said water-bearing strata, an outer liner spaced fromsaid inner liner and extending solely through said water-bearing strata,and a moistureproof barrier disposed between said inner and outer linersand extending solely through said water-bearing strata to preventseepage of moisture through said inner liner and into said shaft, theexterior surface of said outer liner being in contact with the earththrou out its length and the exterior surface of said inner liner mg incontact with the earth solely in that portion thereof which extendsdownwardly into the earth beyond said water-bearing strata.

2. A mine shaft in accordance with claim I, wherein said moistureproofbarrier is composed of sheets of moistureproof material, which expandsupon contact with moisture.

3. A mine shaft in accordance with claim 2, wherein adjacent edges ofsaid sheets of moistureproof material are overlapped.

4. A mine shaft in accordance with claim 3, wherein said moistureproofbarrier is formed of bentonite.

5. A mine shaft in accordance with claim 5, wherein said moisture proofbarrier is provided with a flexible backing sheet on at least one sidethereof.

6. The method of constructing a waterproof mine shaft, which passesthrough a water-bearing strata in the earth comprising those steps ofexcavating the earth to provide a shaft extending into the earth belowand beyond said water-bearing strata or greater diameter than thediameter of said shaft which extends into the earth below and beyondsaid waterbearing strata, inserting an outer liner of an externaldiameter substantially the same as the diameter of the excavated shaftwhere it passes through said water-bearing strata inserting amoistureproof barrier into said shaft in engagement with said outerliner and then inserting into said shaft an inner liner of substantiallythe same external diameter as the diameter of said shaft where it passesinto the earth below and beyond said water-bearing strata, inserting theinner liner into said shaft so that the external surface of the innerliner is in contact with the earth where said inner liner extends intothe earth below and beyond said water-bearing strata, and said innerliner is so inserted into the shaft that its external surface is inabutment with said moistureproof barrier where said inner liner extendsthrough the water-bearing strata of said shaft.

7. The method of constructing a waterproof mine shaft in accordance withclaim-6, wherein the shaft passes through a water-bearing strata in theearth and the method consists of forming said outer liner of a lengthsubstantially the same as the depth of said water-bearing strata andforming said moistureproof barrier of substantially equal length to thelength of said outer liner, and forming said inner liner of a lengthgreater than the length of said outer liner.

1. A mine shaft passing through a water-bearing strata in the earth,including an inner liner passing through and extending downwardly intothe earth beyond said water-bearing strata, an outer liner spaced fromsaid inner liner and extending solely through said water-bearing strata,and a moistureproof barrier disposed between said inner and outer linersand extending solely through said water-bearing strata to preventseepage of moisture through said inner liner and into said shaft, theexterior surface of said outer liner being in contact with the earththroughout its length and the exterior surface of said inner liner beingin contact with the earth solely in that portion thereof which extendsdownwardly into the earth beyond said water-bearing strata.
 2. A mineshaft in accordance with claim 1, wherein said moistureproof barrier iscomposed of sheets of moistureproof material, which expands upon contactwith moisture.
 3. A mine shaft in accordance with claim 2, whereinadjacent edges of said sheets of moistureproof material are overlapped.4. A mine shaft in accordance with claim 3, wherein said moistureproofbarrier is formed of bentonite.
 5. A mine shaft in accordance with claim5, wherein said moisture proof barrier is provided with a flexiblebacking sheet on at least one side thereof.
 6. The method ofconstructing a waterproof mine shaft, which passes through awater-bearing strata in the earth comprising those steps of excavatingthe earth to provide a shaft extending into the earth below and beyondsaid water-bearing strata or greater diameter than the diameter of saidshaft which extends into the earth below and beyond said water-bearingstrata, inserting an outer liner of an external diameter substantiallythe same as the diameter of the excavated shaft where it passes throughsaid water-bearing strata inserting a moistureproof barrier into saidshaft in engagement with said outer liner and then inserting into saidshaft an inner liner of substantially the same external diameter as thediameter of said shaft where it passes into the earth below and beyondsaid water-bearing strata, inserting the inner liner into said shaft sothat the external surface of the inner liner is in contact with theearth where said inner liner extends into the earth below and beyondsaid water-bearing strata, and said inner liner is so inserted into theshaft that its external surface is in abutment with said moistureproofbarrier where said inner liner extends through the water-bearing strataof said shaft.
 7. The method of constructing a waterproof mine shaft inaccordance with claim 6, wherein the shaft passes through awater-bearing strata in the earth and the method consists of formingsaid outer liner of a length substantially the same as the depth of saidwater-bearing strata and forming said moistureproof barrier ofsubstantially equal length to the length of said outer liner, andforming said inner liner of a length greater than the length of saidouter linEr.